Grey’s Anatomy Casts Amy Acker As Derek’s Sister

Grey’s Anatomy fans are about the get to know Derek’s fourth sister. 

Multiple outlets confirm that Amy Acker, star of The Gifted, Angel, and Person of Interest has been cast to play Kathleen, Derek Shepherd’s (Patrick Dempsey) mysterious sister.

After fifteen seasons fans will finally get to see Kathleen Shepherd in an episode that focuses almost exclusively on Amelia Shepherd, played by Caterina Scorsone. Kathleen, who is a doctor like the rest of her siblings, specializes in psychiatry. 

While her appearance has been limited to one episode, it is a big deal in the history of Grey’s as only three out of the four sisters appeared on the ABC medical drama. We’ve briefly met Liz (Neve Campbell) and Nancy (Embeth Davitz) and Amelia (Scorsone), who is a series regular. 

Grey’s Anatomy airs Thursdays on ABC.